A radial compressor is known as a kind of compressor. In a radial compressor, gas flowing out from an impeller is introduced into a scroll portion having a flow path formed in a spiral shape, and discharged by being guided in a circumferential direction. External dimensions of the scroll portion gradually increase from a winding start side to a discharge side.
Here, as in the radial compressors described in Patent Document 1 and 2, for example, in some cases, a casing for a radial compressor used in a turbocharger of an automobile is made of resin for weight reduction or the like.